An absorbent composite is a component of a disposable absorbent garment. Such garments include, but are not limited to, infant diapers or training pants, adult incontinence products, and feminine hygiene products. Typically, the absorbent composite comprises mixtures of fibrous material (e.g., wood pulp or fluff) and a superabsorbent polymer (SAP) that are sandwiched between strata, such as tissues, nonwovens, and permeable and impermeable films.
It is known to use continuous tow in the manufacture of absorbent composites. See Japanese Kokoku 60-26537, US SIR H1565, and U.S. Pat. Nos. 6,068,620; 6,253,431; and 6,543,106. Each is discussed below.
Japanese Kokoku 60-26537 discloses an absorbent structure made of crimped acetate tow and pulverized pulp but no SAP. Referring to FIG. 4, the process for making the absorbent structure is shown. Tow is removed from a bale and is spread by an air banding jet 14. The tow is then de-registered between roller pairs 16, 17. The de-registered tow is further spread and given a uniform density by a second air jet 18. Pulverized pulp 21 is spread on to opened tow after it leaves the second air jet. Thereafter, absorbent sheets are added and the absorbent pad is folded into its final form.
U.S. Statutory Invention Registration H1565 discloses an absorbent structure made of crimped acetate tow and SAP that is preferably adhered to the opened tow by a binder. The tow is opened with a Korber & Co. Model AF2 machine (a common machine used in the manufacture of cigarette filters) and subsequently a mixture of binder and SAP or binder then SAP is added to the tow.
U.S. Pat. No. 6,068,620 discloses an absorbent core made of fibrous crimped acetate tow and SAP between an upper and lower layer. Referring to FIG. 7, SAP is added to the tow via a mixing chamber.
U.S. Pat. Nos. 6,253,431 and 6,543,106 disclose a method of making an absorbent structure from crimped acetate tow and SAP. Referring to FIG. 1, tow from a bale is spread by a banding jet 130. The tow is then partially de-registered (or opened) through the roller assemblies 40, 64, 70. Each roller assembly has a metal roller 42, 62, 72 and a rubber roller 44, 64, 74. Optimally, a liquid is applied to the opened tow by liquid additive assembly 80. The tow is then further opened, shaped in air jet 240. Solid substances, such as SAP, are added after the fully opened and shaped tow emerges from jet 240. Solid substances are added via a vibratory feeder.
There is, however, a need for more practical processes and apparatus to make an absorbent composite.